Method of coloring enamels and the like.



stannic oxid.

ll] iarrian stria ions JOSE]? WEBER, OF ESSEN-ON-THE-RUHB, GERIVIANY, ASSIGNUR TO GOLDSGHIVI v DETINNING COMPANY, OF NEW YORK, N. 3%., A CGRPOBAIION C913 NE'W' Specification of Letters Patent.

No Drawing.

To all whom it may, concern:

Be it known that I, Josnr Vfnnnn, subject of the King of Prussia, and resident of Esseiron-the-Ruhr, in the Province of the Rhine, Germany, have invented a certain new and useful Method of Coloring Enamels and the like, of which the following is a specification.

The invention relates to the method of coloring enamels, glazes and the like.

In the manufacture of opaque enamels andthe like as heretofore practised, stannic oXid has been largely employed as the most satisfactory agent for producing the necessary opacity. Owing to the high cost of stannic oxid, many attempts have been made to produce a satisfactory substitute therefor, usually in the form of otherinetal compounds, but such substitutes have not been productive of satisfactory results. Among other such metallic compounds suggested as substitutes for stannic oXid, calcium stannate containing water and represented by the formula CasnO ArHfl) has been. employed, b lle results have been unsatisfactory, and the enamel to which this substitute is applied lacks many of the desirable characteristics of similar enamels in which stannic oxid is used for the opacity producing agent.

It has been found, according to the present invention, that anhydrous stannate of calcium possesses certain distinct physical properties which render it particularly effective as an opacity producing agent for enamels and the like, quite equal to that of Furthermore, the compound, when so applied to enamels is affected but very slightly by acids, effectively resists high temperatures and can heapplied with the enamel to the articles to be treated very readily to produce a smooth even coating.

It has been found that the o acity produc 'ing qualities of anhydrous ca cium stannate are, in large measure, dependent upon the method of manufacturing the compound and that when the said compound is formed as a reroute a, rare.

Application filed November 27, 1914. Serial Ito. 874,315.

finely divided precipitate from a suitable solution, and subsequently treated to render it anhydrous, the opaquing qualities are en-' hanced to high degree. An anhydrous stannate of calcium, of large volume, and possessing the other above named advan tag'eous qualities may he obtained in the following manner: An alkaline solution of stannic oxid is treated with a soluble cal ,cium salt, for example chlorid of calcium which precipitates calcium stannatc in finely divided form. it sutlicient quantity of acid, such as hydrochloric acid is then added to the solution for the purpose of neutralizing the same, and the precipitate containing; stannate of calcium and Water is separated from the solution by any appropriate means after which it is dried and calcined to entirely eliminate the water. It is found desirable to add the acid in order to remove any excess of the alkaline component. The resultant product of the foregoing process, containing about 72 per centof stannic oxid, when applied in the manufacture of white and opaque enamels and the like is found to equal the more expensive pure stannic oxid n opaquing qualities, resistance to acids and high temperatures, and enables the enamels to be laid. on quite as effectively as does pure stannic OXiCl. in all these properties, the new opacity producing agent is far superior to the forms of water containing stannate of calcium as heretofore employed.

What I claim is:-

1. The method of coloring enamels, which consists in incorporating in the enamel, an opaque colorant comprising anhydrous stannate of calcium.

2. The method of coloring enamels, which consists in incorporating in the enamel, an opaquecoloraut comprising neutralized an hydrous stannate of calcium.

JOSEF WEBER. [1,. 8.]

Witnesses HELEN Norm,

ALBERT Nurse.

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